Al-Cu 楔型打線在電遷移實驗下之破壞機制

Failure Mechanism of Al-Cu Wedge-wedge Bonding under Electromigration Test

曹嚴文(Yan-Wen Tsau)

指導教授 ： 歐陽汎怡

國立清華大學/原子科學院/工程與系統科學系/碩士(2017年)

摘要

打線是一種被廣泛應用在電子產品中的接合技術，主要於導通訊號，由於鋁金屬有著導電性佳、便宜及質地軟的特性，鋁打線很有潛力能取代金線以及銅線。本研究即是研究接合在銅基板上、直徑為2 mil的鋁線在攝氏150度、2 和 7×10^4 A/cm^2電遷移條件下的微結構改變及破壞機制。經實驗發現電阻會先下降而後上升，直到鋁線熔毀。且雖然電遷移後介金屬化合物(IMC)的成長並不明顯，但當電子流從Cu流向Al時，焊點介面的IMC厚度通常比相反電子流流向的IMC厚。並且實驗後還發現鋁線內的晶粒大幅成長而形成竹狀結構，且在鋁線表面靠電子流從Cu流向Al的一側有類似竹節的形狀產生。此次研究將會針對電遷移實驗後試片造成電阻、接點微結構及鋁線表面形貌的機制進行探討。

關鍵字

Al打線 ； 電遷移 ； 高功率模組 ； 介金屬化合物

並列摘要

Wire bonding technology has been utilized in semiconductor packaging industry for electrical connections. Due to low cost, good conductivity, softness and the ability to be bonded under room temperature, Al wire bonding has been considered as a potential candidate to replace the Au and Cu. This study investigates microstructural evolution and failure mechanisms of 2 mil Al wedge-wedge bonding bonded on Cu pad under current density of 2 and 7×10^4 A/cm^2 at 150 ℃. During electromigration tests, resistance decreased first and then increased till wires failed. Though the growth of intermetallic compounds (IMC) at the bonded interface change insignificantly after electromigration tests, the thickness of IMCs at the bonding interface where electron flowed form Cu to Al is usually larger than that at the interface where electron flowed in the opposite direction. Furthermore, considerable grain growth, bamboo structure and bamboo nodes were observed in Al wires. The corresponding mechanism of IMC growth at the interface, resistance change and as well as the formation of bamboo nodes were discussed.

並列關鍵字

Al wire bonding ； electromigration ； power modules ； IMC

參考文獻

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